Stacked electrode assembly for electron discharge devices



w. s. BRIAN 2,441,792.

STACKED ELECTRODE ASSEMBLY FOR ELECTRON DISCHARGE DEVICES May 18, 1948.

Filed Oct. 4, 1944 5 Sheets-Sheet l INVENTOR. ZULZZLO/M/ 5: 5mm, 12% My May 18, 1948. w 5, BRIAN 2,441,792

*STAGKED ELECTRODE ASSEMBLY FOR ELECTRON DISCHARGE DEVICES Filed 0013. 4, .1944 3 Sheets-Sheet 2 35 IN VEN TOR.

May 18, 1948. w. s. BRIAN ,441,792

STACKED ELECTRODE ASSEMBLY FOR ELECTRON DISCHARGE DEVICES Filed 001;. 4, 1944 3 Sheets-Sheet 3 IN V EN TOR.

? aientecl May 18 1948 STACKED ELECTRODE ASSEMBLY FOR ELECTRON DISCHARGE DEVICES 4 William S. Brian, Owensboro, Ky., assignor, by

mesne assignments, to General Electric Company, a corporation of New York 7 Application October 4, 1944, Serial No. 557,126

34 Claims. 1

This invention relates to electron discharge devices and, while it is of general application, it is particularly suitable for embodiment in devices of the type to be operated at high frequencies or ultra-high frequencies and. to devices of the duplex or dual-purpose type. .The invention also relates to an electrode assembly of general application but which is particularly suitable for use in the devices of the invention.

Heretofore general purpose vacuum tubes adapted for mass production methods at relatively low cost have been manufactured in large quantities. These tubes, however, have not been vice which is well suited for a wide variety of applications and which is at the same time well adapted for mass production methods.

It is an object of the invention, therefore, to provide a new and improved electron discharge therein. The lead-in conductors are connected to the electrode connections and there is provided means enclosing opposite sides of the electrode assembly and sealed to opposite sides of the stem.

Further in accordance with the invention, the electrode assembly incorporated in the electron dischargedevice described comprises a cathode structure including a cathode and a member surrounding the cathode and having peripheral supporting provisions and a cylindrical shell of insulation material engaging the supporting provisionsj -The electrode assembly also includes a plurality of spacer rings of insulation material stacked upon the member within the shell and control electrode means supported between predetermined adjacent ones of the spacer rings .The assembly also includes means for retaining the spacer-rings and the control electrode means Within the shell. Further, in accordance with the invention, the cathode of the electrode assembly is of the equipotential type and comprises an annular hollow conductive member having an electron emissive coating on at least a portion of the surface thereof and a heating element disposed within the member. 7

Further, in accordance with the invention,

each of the control electrodes of the assembly of the invention comprises an annular metallic supdevice which is simple and inexpensive in construction and readily adapted to mass production by automatic machinery and one which overcomes one or more of the above mentioned shortcomings and limitations of the general purpose special purpose tubes of the prior art and yet one which is of low cost and suitable for mass production by automatic machinery and for use as a general purpose tube.

It is another object of the invention to provide a new and improved electrode assembly which is of general application but which is particularly suitable for use in the new and improved electron discharge device of the invention. 3

In accordance With the invention, there is provided an electron discharge device comprisingan electrode assembly having a plurality of electrode connections and an annular sealing member or stem surrounding the assembly and including a plurality'of radial lead-in conductors sealed porting member, a wire screen covering the opening in the member and bonded to the periphery thereof, the screen having a dish-like configuration with a substantially plane bottom.

' Further, in accordance with the invention, the

sealing stem or lead-in sealing member for the electron discharge device comprises an annular member of fusible vitreous material formed with circular cross sections.

For a'betterunderstanding of the invention, together with other and further objects thereof, referenceis had to the following description taken in connection with. the accompanying drawings while its scope will be pointed out in the appended claims.

Referring now to the drawings, Fig. 1 is an enlarged cross-sectional detail of a complete electron discharge device embodying the invention; Fig.2 isan exploded perspective view of thecath- 3 ode member of the electrode assembly of the device of Fig. 1; Fig. 3 is a perspective view of a control electrode member suitable for embodiment in the device of Fig. 1; Fig. 4 is a perspective view of the anode of the electrode assembly of the device of Fig. 1; Fig. '5 is a plan view of the complete cathode structure of the electrode assembly of the device of Fig, 1; Fig. 6 is a perspective aiding in accurately maintainingthe desired electrode spacings.

view of the sealing stem of the device of Fig; 1. at j an intermediate stage in its fabrication; Fig. 7 is an elevational view, partly in section, of the device of Fig. 1; Fig. 8a is a longitudinal view, partly in section, of a modified form of electron discharge device of Fig. 1 suitable for use as a pin-base type of device; Fig. 8b is an end view of the device The cathode structure ll also includes an annular supporting element surrounding the member I la. and thermal expansion means Ilj for supporting the member lla from the annular element. Specifically, the annular element comprises a pair "of opposed annular members llz',

of Fig. 8a, and Fig. 9 is a perspective view of an 7 alternative form of anode suitable for use in the device of Figs. 8a and 81),

Referring now to the several figures of the drawing, there is illustrated an electron discharge device embodying the invention and comprising a novel unitary electrode assembly disposed in a novel form of envelope, together with provisions for making external connections to the electrodes and a novel stem or seal. The electron discharge device of the invention comprises an elongated cylindrical unitary electrode assembly l0, Fig. 1, which may be either of the single electron stream type or, as illustrated, of the duplex type comprising two independent electron discharge paths.

The electrode assembly ll! includes a. cathode structure ll, Fig. 5, of any suitable type, preferably comprising an electron emissive cathode member He of the equipotential type shown more clearly in the perspective view of Fig. 2. The cathode member ,I la is in the form of an annular hollow conductive member formed of two opposed annular. trough-like elements I lb and He, shown as opened like a clam shell in Fig. 2. The elements llb, llc have'an electron emissive coating of any well-known type on at least a portion of the surfaces thereof, preferably on only the upper and lower faces thereof, A heating element lid is disposed within the cathode member lla and is preferably constructed as an extended n oninductive bifilar insulated helical winding Md. The wire forming the heating element l'ld may be coated with an insulating composition before winding or the winding may be coated after it is wound. The winding I lot is of the same diameter as the maximum inner diameter of the cathode member Ho and, after winding and coating, it maybe collapsed axially to fit into the, member 'lla. *An insulatingcoating suitable 'for the heat.- ing element lld may be finely divided magnesia or alumina in a nitro-cellulo'se binder and the coating should be made as thin as practicable in order to minimize the thermal lag of the heating "element. The winding 1 Id is provided with terminals l le which project from the cathode member I la through a radialcond'uit' formed by the opposed trough-like radial extensions llf, llg

formed in the periphery'or the elements 1 lb, H c, respectively. The elements "I lb and lljc may be electrically connected to form a unipotential cathode member, or they may be separated by a film, coating, or layer of insulation material to provide two electrically isolated cathodemembers each of the equip'otential type. With this construction, two electrically independent electron discharge devices may be provided as described hereinafter.

The cathode member a is also provided with a plurality of radially extending supporting tabs llh formed at the rims of the members I lb and Ht" surrounding the cathode member lla and a plurality of semi-rigid or deflectable wires H7 welded or otherwise bonded to the tabs llh and disposed between and welded or otherwise bonded to both of the members llz'. This semi rigid support of the cathode member ll 'a'permits relative expansion and contraction between themember lla. and the supporting element without warping of either. The opposed members lli comprise opposed peripheral supporting means or retaining'flanges for the electrode sub-assemblies to be. described. Suchsupporting means may be either internal or external to the sub-assemblies to be supported and may be inthe form "of tabs, lugs, or the like or, as illustrated,in the form of peripheral opposed rims so that the members Hi, l it are essentially cup-shaped members with their central portions deleted.

In the duplex ty pe of tube illustrated in Fig. 1, there is provided a pair of electrode sub ass'em blies disposed on the opposite sides of the cathode structure ll, eachlcomprising a plurality of elements which may be identicaland therefore are identified by the same reference numerals, one set being primed to distinguish it from the other. Each of theseelectrodesub-assemblies comprises a cylindrical shell l2 of insulation material providedwith a connection aperture suchas a longitudinal slot lZa. The shell I2 is. preferably formed of ceramic material such as steatite or an alumina-silica mag-nesia compound of the type commercially available as Alsimag." The shell l2 engages thev peripheral supporting. pro-.- visions of the cathode structure ll, that is, it is seated in and irictionally engages the cupshaped member lli.k

The electrode assembly also includes a 'plurality of identical interchangeable spacer rings l3 and a spacer ring ld, all preferably a ceramic of the, same type as the shell l2, stacked upon the member I I2 of tlhe cathode structure within the shell l2 and loosely fitting within such shell. Between predetermined adjacent ones. of the spacer rings 13 and l4 are supported control electrode means, preferably a plurality of con- 'trol grids or electrodesl'e'. lliand l'l:,. which are supportedbetween each adjacent pair of rings. In case the supporting rings of the electrodes l5, l6, and I"! are coated with a film or layer of insulating material, the spacer rings l3 and H need'not be formed of insulation material. The oute'rring M is somewhat wider than the 'rings lIS in the specific structure illustrated. tofacili- 'tate spacingthe electrodes by the desired amounts.

The control electrodesyli'a, l6 and H 'may' be identical but are preferably of diiierentzdesigns 'best suited to the particular functions. thereof.

In the particular tube illustrateifthese control electrodes normally comprise a control grid, a screen grid and a suppressor grid. The construc- We of the desired mesh for the particular control electrode under consideration is deformed by a suitable die into a dish-like configuration and is then placed over the ring a to cover the openingtherein and is welded, hard-soldered or otherwise bonded thereto around the periphery thereof. The deformed portion of the screen l5c extends through the rim I51) and, in the specific type of tube structure illustrated, has a plane bottom of an accurately predetermined depth below the upper face of the member i5a and in a plane parallel thereto, as clearly shown in Figs. 1 and 3. f

The depths of theseveral control electrodes are so related to the width of the spacer rings it as to determine accurately the desired spacing between the controlelectrode l5 and the cathode member Ha and between the control electrodes l5, l6 and I1. Generally, the control electrodes have difierent depths and are formed with tapered sides to permit them to nest within each other, thereby providing electrode spacings much less than and independent of the width of the spacer rings l3. For example, in the structure illustrated it is seen that the spacing between the control electrode l5 and the cathode member Ila is very small and is an extremely small fraction of the width of the spacer member l3, this very close spacing imparting a very high mutualconductance characteristic to the device. Similarly, by nesting of the grid 55, which may be the screen grid, within the grid l5, the spacing of these two grids may be made small. On the other hand, by inverting the outer control electrode H, which may be the suppressor electrode, it may be widely spaced from the other control electrodes but disposed closely to the anode, which is the desired relationship. At the same time, the spacer rings I3 are of a substantial width so that they have a reasonablestructural strength and are all of the same width, thus making them interchangeable and minimizing the number of forming dies required in their molding.

The control electrodes [5, l6, and 11 are provided with connector means such as the connectors l5d, Hid and l'ld respectively, extending through the slot l2a in the shell I2. As shown in Fig. 1, the two shells have their slots diametrically opposed and each group of electrodes has its electrode connections extending through its respective shell aperture or slot, thus obtaining a maximum spacing between the electrode connections of the two groups of electrodes and minimizing the coupling therebetween.

The electrode assembly also is provided with means for retaining the spacer rings l3 and I4 and the several control electrodes within the shell l2. In the preferred embodiment, this means is a disk-like anode 18 disposed within the shell l2 beyond the several control electrodes and including provisions for engaging the shell to retain suchelements therein, for example, a plurality of radially extending upwardly bent .tabs l8a adapted frictionally to engage the internal periphery of the shell l2. The configuration of the anode I8 is best shown in Fig. 4 from which it is seen that it is formed with an annular stifie'ning groove lBb connected with threeradial stiflening grooves 180. Supported from the center of the anode l8 and within the stiffening groove l8b is a rigid terminal or split eyelet |8d welded or otherwise bonded to the anode for receiving a terminal connection and constituting a support for the electrode assembly. Thus anode I8 comprises means for retaining the several elements of the assembly in their proper relative position while. the electrode assembly is retained in position by the frictional engagement of the shell l2 assembly.

The electron discharge device of the invention also includes an annular sealing member surrounding the electrode assembly ID with the axis of the assembly disposed generally along a diammeter of the annular member. The sealing member 19 is preferably in the form of an annulus of fusible vitreous material and formed'with a plurality of deep radial slots l9a in one face thereof, as illustrated in Fig. 6. A lead-in conductor 20 is disposed in each slot and the slots are then closed by the application of heat and pressure to the member H) to fuse the member to the conductors 20 and form a vacuum-tight seal. The electrode connections I511, "id and Hi! are connected to the radial lead-in conductors 20, preferably the electrode connections of each electrode sub-assembly or space-discharge path being connected to the ones of the lead-in conductors 20 extending through the side of the stem l9 adjacent its respective connection aperture lZa or In, as indicated in Fig. 6, while the cathode terminals He may be connected to any appropriate ones of the conductors 20. Further, the

electrode connections may be so disposed and .connected to such lead-in conductors that the screen and suppressor connections are interposed between and tend to shield desired ones of the control grid, cathode and anode connections, thereby minimizing the inter-electrode capacitances of the device. The connections 15d, Hid and l'ld may be of flexible metallic ribbon, such'as nickel, welde'd or otherwise bonded to the rims of their respective electrodes. It will be noted that the connections from the rigid anode terminals I8d to their respective lead-in conductors 20 constitute the sole support of the electrode assembly H) from the sealing stem l9.

The electron discharge device also includes means, preferably a pair of generally hemispherical metallic shells 2| enclosing opposite sides of the electrode assembly and sealed to opposite sides of the member I9, as indicated in Fig. 1, and forming with the member I!) the envelope of the device. The shells 2| are formed of material having a coeflicient of thermal expansion matching that of the glass member l9; for example; the member 19 may be formed of a lead-silica glass having a high lead content while the shells 2| may be formed of a ferro-chrome alloycontaining 25% to 35% chromium.

While it will be apparent to those skilled in the art that the physical dimensions of the electron discharge device of the invention will varywithin wide limits in accordance with the particular performance characteristics required,"there follow the dimensions of one electrical discharge or ring 31, Fig. 9.

device embodying :theinventionand designed or as. a radio-frequency amplifier:

'Inches "Outer diameter, member. 19 1.500 Overall aheight 1 .187

"Shell Outer diameter 70.660 Width 0.325 Thickness of shell 0.040 Spacer rings:

Outer-diameter 0.565 Width 0.050 Thickness 0.075 Cathode :member I la:

:Outer-di'ameten 0.300 Innerdiameter; 0.200 Thickness 0. 030 :Control electrode iii-depth 0.037 Control electrode iii-depth 0.080 Control electrode !'l-depth- 0937 spacings: J

Control grid i5'-scr een 1'5 0.013 Screen IE-suppressor I?! 0.167 Suppressor il -anode is 0.038

The electron dischargedevice-described may" be fabricated in any desiredmanner but it is preferably constructed in accordance with the method disclosed and claimed in-my-copending application entitled Method of and apparatus for manufacturing electron discharge devices, Serial l N0. 564,7 68, filed-November 23, 1944, which issuedthus improvingthe heat-dissipating properties andincreasing the power capacity of the device. Such an arrangement may be embodied in a structure of the type represented in'lligs. 8a and 8b. The'electrodeassembly 30 of this form of the invention may be similar tothat of Fig 1 except that 'the connection siots 42a "and 42a are in alignment and except that the anode-l3 is omitted and replaced by azretain'ing element The retaining ring .31 is provided with projecting-tabsticfor frictionally engaging the internal periphery of the-shell i2 to retain several spacer rings and'contro-l'electrodes within the shell. 1* is also, icrmed'with 'a' plurality offstifi radial spokes dib which are supporting terminal tie for porting lead-in conductors, as well'as the electrode lead-in conductors 33, are sealed inasuitable stem or sealing base "34, the slots "in the shells'of the electrode assemblyzl opening in the same general direction, being directed downwardly toward the'base 34 :tominimize the lengths of thele'ad-in conductors. In this type of construction the outer shells". 12. may, if desired, be

made as a single continuous slotted shell instead .of in two parts, thecathode *supporting ring being constructed similar to the grid-supporting ringand engaged between adjacent spacer ring withinlthe retainer shell.

The assemblyill is enclosed in a metallic envelope' creasing ;35.:sealed at its "open'end to the periphery of the stem or base 3t. It will be understood that the modification of Figs. .80; and

-8b may include any desired arrangement of leadin conductors an-dm-ayyif desired, be provided with a conventional pin base (not shown) for mounting.

The operation ofthe improved electron discharge devices illustrated and described above is conventional andlneed not be described-in detail. However, it is seen that this form of electron discharge device'has the desirable charac- 'teristics of the several special purpose "devices of the priorart; that the various electrodes of the device andthelr supporting elements'are such as to produce an extremelyrigidstructure capableof withstanding substantial shock or vibration without damage and without substantially altering the'p'hysi'cal spacings of the elements or electrical characteristics of the device. At the sametime the spacings between the cathode and the first control electrode and between the-several control electrodes may be accurately predetermined at very small values, imparting a very high mutual conductance and accurately reproduceablecharacteristics. At the same time, due to the short lead-in conductors and electrode connections the inherent impedance 'of the lead-in conductors and electrode c0nnections is reduced to a minimum. Due to the complete shielding of the inner control electrode displacement of the device is much less than prior art general purpose vacuum tubes. At the same time the sealing structure is extremely simple and the whole assemblyoperation is one Which'can be accomplished readily on a mass production basis by assembly line methods as described and claimed in my aforesaid copending application. Because of its adaptability to mass production, the electrondischarge device of the invention is capable of extremely low cost production and'therefore capable of use as a general purpose vacuum tube, although combining the advantageous characteristics'of the several special purpose tubesof the prior art.

While there have been described what are-at present considered tops the preferred embodiments of the invention,- it will be apparent to those skilled in the art that various changes and 'inoidifications-may be made therein without departing from:the spirit or scope of the invention.

What is claimed as new is: 1. An electron-discharge device com-prisinga unitary electrode assembly having a, plurality of electrode connections including rigid terminals at opposite ends thereof, .an' annular sealing .member surrounding. said assembly and including a pluralityoiradial lead-in conductors sealed therein,.said conductors being connected to said electrode connections, said lead in conductors connected to said rigid terminals-constituting the sole support of said electrode assembly, and means enclosing opposite sides'of'said electrode assembly and sealed to opposite sides of said member.

2. An electron-discharge devicecomprising, a

unitary duplex electrode assembly-having a plurality of electrode connections Lincluding an anode at each end thereofanda rigid terminal connected thereto, an annular sealing member surrounding said assembly and including a plurality of radial lead-in conductors sealed therein, said conductors being connected to said elec;

means enclosing opposite sides of said electrode assembly and sealed to opposite sides of said' member.

3. An electron-discharge device comprising, a duplex electrode assembly including two. groups of electrodes, a ceramic shell surrounding each of said groups, said shells having diametrically opposed connection apertures therein, and a plurality of electrode connections for each of said groups of electrodes extending through one of said apertures, an annular sealing member surrounding said assembly and including a. plurality of radial lead-in conductors sealed therein, each of said plurality of electrode connections being connected to the ones of said conductors extending through the side of said member adjacent its respective aperture, and means enclosing opposite sides of said electrode assembly and sealed to opposite sides of said member.

4. An electron-discharge device comprising, an electrode assembly having a plurality of electrode connections, an annular sealing member surrounding said assembly and including a plurality of radial lead-in conductors sealed therein, said conductors being connected to said electrode connections, and a pair of metallic shells enclosing opposite sides of said electrode assembly and sealed to opposite sides of said member.

5. An electron-discharge device comprising, an electrode assembly having a plurality of electrode connections, an annular sealing member surrounding said assembly and including a plurality of radial lead-in conductors sealed therein, said conductors being connected to said electrode connections, and a pair of generally hemispherical metallic shells enclosing opposite sides of said electrode assembly and sealed to opposite sides of said member.

6. An electron-discharge device comprising, an electrode assembly having a plurality of electrode connections, an annular sealing member surrounding said assembly and including a plurality of radial lead-in conductors sealed therein, said conductors being connected to said electrode connections, and a pair of metallic shells enclosing opposite sides of said electrode assembly and sealed to opposite sides of said member and serving as anode means for the device.

'I. In an electron-discharge device, a unitary electrode assembly comprising, a cathode struc-- ture including a cathode and a member surrounding said cathode and having peripheral retaining means, a cylindrical shell of insulation material engaging said retaining means, a plurality of spacer rings stacked upon said member within said shell, electrode means supported between predetermined adjacent ones of said spacer rings,

and means for retaining said spacer rings and said electrode means within said shell. I

8. In an electron-discharge device a unitary electrode assembly comprising, a cathode structure including a cathode, an annulanmember having peripheral retaining means, thermal expansion means supporting said-cathode from said member, a cylindrical shell of insulation-mate rial engaging said retaining means, a. plurality of spacer rings stacked upon said member within electrode assembly comprising, a cathode structure including a cathode, an annular member having peripheral retaining means, a plurality of deflectable supporting wires bonded to said cathode and to said member, a cylindrical shell of insulation material engaging said supporting provisions, a plurality of spacer rings stacked upon said member within said shell, electrode means supported between predetermined adjacent ones of said spacer rings, and means for retaining said spacer rings and said electrode means within said shell.

10. In an electron-discharge device, a unitary electrode assembly comprising, a cathode structure including a cathode and an annular cupshaped member surrounding said cathode, a cylindrical shell of insulation material seated in and frictionally engaging said cup-shaped memher, a plurality of spacer rings stacked upon said member within said shell, electrode means supported between predetermined adjacent ones of said spacer rings, and means for retaining said spacer rings and said electrode means within said shell. I

11. In an electron-discharge device, a unitary electrode assembly comprising, a cathode structure including a cathode and a member surrounding said cathode and having peripheral retaining means, a longitudinally slotted cylindrical ceramic shell engaging said retaining means, a plurality of spacer rings stacked upon said member within said shell, electrode means supported between predetermined adjacent ones of said spacer rings and provided with connector means extending through the slot in said shell, and means for retaining said spacer rings and said electrode means within said shell.

12. In an electron-discharge device, a unitary electrode assembly comprising, a cathode structure including a cathode and an annular cupshaped member surrounding said cathode, a longitudinally slotted cylindrical ceramic shell seated in and frictionally engaging said cupshaped' member, a plurality of spacer rings stacked upon said member within said shell, electrode means supported between predetermined adjacent ones of said spacer rings and provided with connector means extending through the slot in said shell, and means'for retaining said spacer rings and said electrode means within said shell.

- 13. In an electron-discharge device, a unitary electrode assembly comprising, a cathode structure including a cathode and a member surrounding said cathode and having peripheral retaining means, a cylindrical shell of insulation material engaging said retaining means, a plurality of spacer rings stacked upon said member within said shell, a plurality of electrodes individually supported between adjacent ones of said spacer rings, and means for retaining said spacer rings and said electrode means within said shell.

14. In an electron-discharge device, a unitary electrode assembly comprising, a cathode structure including a cathode and a -member 'sur-- rounding said cathode and having peripheral re-- taining means, a cylindrical shell of insulation material engaging said retaining means, a pluralityof identical interchangeable ceramic spacer rings stacked upon said member within said shell, electrode means supported between predeter-' mined adjacent ones of said spacer rings, and means .for retaining said spacer rings and said electrode means within said shell.

15. In an electron-discharge device, a unitary engaging said retaining means, a plurality. of

identical interchangeable ceramic spacer rings stacked upon saidmember Within said'shell, a control electrode supported between predetermined adjacent ones of said spacer rings'and having a dish-like configuration of a depth related to the Width of said spacer rings toj ive-thedesired control electrode-cathode spacing, and means for retaining said spacer rings and said control electrode within said shell;

16; In an electron-discharge device, a unitaryelectrode assembly comprising, a cathodestructure including a cathode and a member surround-,- ing' said cathode and having peripheral retaining means, a. cylindrical shell of insulation material engaging said retaining means, a plurality of identical interchangeable ceramic spacer rings.

stacked upon said member within said shell, a

plurality of electrodes individually supported ing said cathode and having peripheral retaining means, a cylindrical shell of insulation material engaging said retaining means, a plurality of identical interchangeable ceramic spacer rings stacked upon said member within said shell, a

' plurality of electrodes individually supported between adjacent ones 'ofsaid spacer rings, said electrodes having dish-like configurations of different accurately predetermined depths and tapered sides to permit nesting thereof, therebyto provide electrode spacings much less than and independent of the width ofsaid spacer rings,

and means for retaining'said' spacer rings and said electrodes within said shell.

18. In an electron-discharge-device, a unitary electrodeassembly comprising, a cathode structure including a cathode and a member surround il'lg' said cathode and having peripheralretaining means, a cylindrical shell of insulation material engaging said retaining means, a plurality" of annular spacer rings stacked upon saidmember within said shell, electrode -means supported between predetermined adjacent ones of, said spacer rings, and an anode disposed withinsaid shell beyond said electrode means.

19. In an electron-discharge device, a unitary electrode assembly comprising, a cathode structure including a cathode and a member surround ing said cathode and having peripheral retaining means a cylindrical shell of insulation material engagingsaid retain ng means, a plurality of-an,- nular spacer rings" stacked uponsaid member within'saidshell. electrode means supported bea tween predeterminedadiacent ones of said spas errings, andan anode disposed within saidshell on the side of saidel'ectrode means opposite said cathode structure including means for engaging said; shell'to retain said s ace-r rings. and

said! electrode means therein 20. In. an electren-discharge devicaa unitary electrode: assembly comprising, a cathode strum e c di a cathode'and a member surrounding said cathode and having peripheral retain- 12 ing means, a cylindrical shell of insulation material engaging. said retaining means, a plurality of annular spacer rings stacked uponsaid member-within said shell, electrode means supported between predetermined adjacent ones of said spacer rings, and an anode disposed within said shellion the sideof said electrode means oppositetsaidcathode: structure and. including a rigid terminal. constituting a support for said. assembly- 2:1; Inan electronedischarge: device, a unitary electrode assembly comprising, cathode structureincludinga cathode and a member surrounding said cathode andv having peripheral "retaining means, a cylindrical-shell of insulation material engaging said'retaining means, a plurality of annular spacer J rings stacked upon said within said shell, electrode means supported between predetermined adjacent ones of said spacer rings, and a disk-like anode including a plurality of radiallyextending' tabs for engaging said shell to retain said spacer rings and, said electrode means therein, said'anode being provided with rigidtennin'al constituting a support for the assembly andbeing formed with a pluralityof leuvers to iacili'tate exhaust of the interior of the assembly.

22. fman. electron-di scharee device, a, unitary lectrod'e-assembly comprising", a cathode struc ture including a cathode and a member surrounding said cathode and having opposed peripheral retaining meansand a pair of'electrode sub-assembli'es disposed onopposite sides of said member, each comprising a cylindrical shell of insulation material engaging said retainer means, a plurality of spacer rings stacked upon said member' Within said shell; el'ect-rodemeans supported betweenpredetermined adjacent ones of said spacer-fings, and means for retaining said spacer rings and said electrode means Withinsaidsheli. 23. In an electron-discharge device, a unitary electrode assembly comprising; a cathodestructurei'ncluding a cathode and a pair of opposed annular cup-shaped members surrounding said cathode, and a pair of electrode subassemblies disposed on opposite sides of said members, each comprisingla cylindrical-shell of insulation material seated in and frictionally engaging its respective eup shaped'member, a plurality of spacer rings stacked upon said'member Within said shell, electrode means supported between predetermined adjacent ones of said spacer rings, and means for retaining said spacer rings and said electrode means Within said shell.

24-. An electron-emissive cathode of the equipotential type for an electron-discharge device comprising; an annular hollow conductive member' havingan electron-emissive coating on at least a portionof the surface thereof, and a heatin element disposed within said member, said member being provided with a plurality of radially extending supporting tabs.

25. An 'electron-emissive cathode of the equipotentialtype for an electron-discharge device comprising, an annular'hollow conductive member having an el'ectron emissivecoating on at leastaportionof the surface thereof, a heating element-disposed within said member, an annular supporting element surrounding said member, and thermal expansion means supporting said member from said; supporting element. 7

26 An electron-emissive cathode of the equipotenti-al type for an electron-discharge device comprisin an annular hollow conductive member' -havin g' an electromemissive coating on at least a portion of the surface thereof, and a heating element disposed within said member, an annular supporting element surrounding said member, and a plurality of semi-rigid Wires bonded to said tabs and, to said supporting ele ment.

27. An electrode for an electron-discharge device comprising an annular metallic supporting member having a curved inner rim projecting from one face thereof, a wire screen covering the opening in said member and bonded to the periphery thereof, said screen extending over the inner surface of said rim and having a dish-like configuration.

28. An electron discharge device comprising a unitary electrode assembly including a plurality of electrodes each having a substantially circular central portion and supporting means extending from the edge of said central portion, a plurality of annular spacer rings of insulating material arranged in a stack with the supporting means of the various individual electrodes arranged between adjacent ones of said spacer rings, means including a pair or members engaging opposite ends of said stack for retaining said rings and electrodes in assembled relation, an envelope, and means engaging at least one of said members for supporting said electrode assembly within said envelope.

29. An electron discharge device comprising a unitary electrode assembly including a plurality of electrodes each having a substantially planar surface and supporting means extending from the edge thereof, a plurality of spacer rings of insulating material arranged in a stack with the supporting means of the various individual electrodes arranged between adjacent ones of said spacer rings, a substantially cylindrical enclosure for retaining said rings and electrodes in assembled relation including a pair of sheet metal mernbers engaging opposite ends of the assembly, an envelope, and means engaging said cylindrical enclosure for supporting said electrode assembly within said envelope.

30. An electron discharge device comprising a unitary electrode assembly including a plurality of electrodes each having a substantially planar surface and supporting means extending from the edge thereof, a plurality of circular spacer rings of insulating material having a uniform outer diameter and arranged in a stack with the supporting means of the various individual electrodes arranged between adjacent ones of said spacer rings, means including a pair of sheet metal member engaging opposite ends of said assembly for retaining said rings and electrodes in assembled relation, an envelope, and means engaging at least one of said metal members for supporting said electrode assembly in spaced relation with respect to the interior walls of said envelope.

31. An electron discharge device comprising a substantially fiat equi-potential cathode having an electron emissive coating on at least a portion of the opposite exterior surfaces thereof, said cathode having supporting means extending from the edge thereof, two stacks of insulating rings, one arranged on each side or said cathode and engaging said supporting means, a plurality of electrodes each including supporting means extending outwardly therefrom and individually received between adjacent ones of saidspacer rings, a cylindrical enclosure for retaining said electrodes and said spacer rings in assembled relation including a pair of sheet metal members engaging the outer ends of said stacks, an envelope enclosing said electrode assembly, and means engaging said cylindrical enclosure for supporting said assembly from said envelope.

32. An electron discharge device comprising a substantially flat equi-potential cathode having an electron emissive coating on at least a portion of the opposite exterior surfaces thereof, said cathode having supporting means extending from the edge thereof, a stack of insulating rings arranged on opposite sides of said cathode and engaging said supporting rings, a plurality of electrodes each including peripherally extending portions individually received between adjacent ones of said spacer rin s, a cylindrical enclosure for retaining said electrodes and said spacer rings in assem led relation, an envelope enclosing said electrode assembly, and means engaging said cylindrical enclosure for supporting said assembly from said envelope.

33. An electrode assembly for an electron discharge device including a plurality of insulating spacer rings of uniform thickness arranged in a stack, a plurality of control electrodes each including a central planar portion and outwardly extending supporting means, the central portions or" said electrodes being oifset different distances with respect to the associated supporting means to produce desired spacing of the central portions of said control electrodes independently of the thickness of said spacers.

34. An electric discharge device comprising a unitary electrode assembly including a plurality of electrodes each having a central portion and a marginal supporting portion extending outwardly from the central portion, a plurality of annular spacer rings of insulating material arranged in a stack with the supporting portions of the various individual electrodes arran ed between adjacent ones of said spacer rings, an envelope and a plurality of lead-in conductors sealed through said envelope and engaging said assembly of electrodes and spacers at opposite ends thereof to maintain said rings and spacers in assembled relation and to support said assembly in insulated relation with respect to the interior of said onvelope in spaced relation with respect to the interior wall thereof.

WILLIAM S. BRIAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,628,982 Hulsizer May 17, 1927 1,677,316 Zworykin July 17, 1928 1,688,991 Schwerin Oct. 23, 1928 1,797,990 Lucian Mar. 24, 1931 1,816,619 Smith July 28, 1931 1,871,363 Fritz Aug, 9, 1932 1,905,692 Edwards Apr. 25, 1933 1,931,737 Parisi Oct. 24, 1933 1,981,669 Ronci et al Nov. 20, 1934 2,030,187 Salzberg Feb. 11, 1936 2,034,571 Found Mar, 17, 1936 2,036,069 Morrison Mar, 31, 1936 2,074,864 Salzberg Mar, 23, 1937 2,099,846 Farnsworth Nov. 23, 1937 2,259,690 Hansen et a1 Oct. 21, 1941 2,284,547 West May 26, 1942 2,308,800 Anderson Jan. 19, 1943 2,348,814 Herriger May 25, 1943 2,413,689 Clark et a1. Jan. 7, 1947 

